Seriously it slows down your machine due to having to scan files. Best option is don't click on questionable links inside questionable popups on questionable websites. Especially ones that say 'Your computer is infected! Click here to clean it!'

If the above is not an option, I use Prevx on my friends' machines when they get spyware or viruses. It's the best, finds crap the others don't find.

Seriously it slows down your machine due to having to scan files. Best option is don't click on questionable links inside questionable popups on questionable websites. Especially ones that say 'Your computer is infected! Click here to clean it!'

If the above is not an option, I use Prevx on my friends' machines when they get spyware or viruses. It's the best, finds crap the others don't find.

Then I uninstall it ...

X2

Don't be stupid and you won't have a problem. I have no virus software and have had 0 issues for a long time. I do random scans with malwarebytes and still have no issues.

Plus don't forget ... If you DO get a virus or spyware, you can install antivirus software, scan, clean, and uninstall. They do their job, but having them on 24/7 is the part that I cannot deal with as it severely affects day to day operation due to constant scanning.

I am a programmer/tech consultant but my friends and family just think I am the IT guy, so I get to fix their computers. Often people complain to me that their PC is running slow. Funny enough, even with antivirus installed, they will still have some spyware that their antivirus cant clean.

I clean it with Prevx and then uninstall their virus software, and just doing those 2 things makes their PC run like new.

Norton works great in my experience, it's not what it was a few years ago. Light on resources, fast, and easy to use. A good alternative is ESET.
MSE did not serve me well, it let malware through on my parent's PC. I also had an unsatisfactory experience with Bitdefender on their PC, it simply stopped starting. I reinstalled and had the same issue. Switched to Norton ... no problems since.

If this is for your home computer you really don't need any anti virus. You don't just get a virus from being on the internet. You have to download sketchy files and run them, open shady email attachments, go to shady websites with outdated browsers full of security holes, never update your os, etc...

With that said AVG and kaspersky are good to check out. There is always norton and mcafee too. They work but are bloated and may slow down your system more. Any anti virus will slow down your system some, but if the system is pretty high end you won't really notice it.

If you ever get a bad virus I wouldn't bother trying to scan for it under the same infected operating system. Instead I'd use something like kasperky rescue disk. You boot up to a linux distro on a flash drive and then scan the fked up drive that way. Trying to boot up a badly infected windows install and run a virus scan from that same install will make you want to shoot yourself.

There are a lot of these review, the funny thing was kaspersky got rated the above avg in a few sites and I know for sure, kaspersky at 2010/2011 blows. I had the enterprise version at work and was replaced with symantec end point protection. I only run symantec now but recenlty (past 2 months), it has not caught a bunch of malware that it should have. I recently added malwarebytes to some of the trouble desktops at work